What makes Tazz such a great commentator for me is his really apparent love of wrestling. It's like watching the show with a friend who gets into it as much as you do. He'll just blurt out exclamations after a good suplex and talk up a good wrestler whether they're a face or a heel. Plus he'll go out of his way to explain the way certain move works, even going so far as to talk about the mechanics behind the bearhug.
He reminds me of a more focused, professional Stevie Ray (who I really wouldn't mind seeing in the color chair on Raw).